The importance of emerging stream insects for the community structure and function of terrestrial systems
Traditionally, ecosystems have been viewed as clearly defined, self-sustained units, and ecological studies have focused on patterns and dynamics within ecosystems. Over the past two decades, however, more and more studies are showing that ecosystems often are intimately connected across ecosystem boundaries via spatial flows of energy that drive community structure and dynamics. The freshwater-terrestrial interface is a typical example where cross-boundary flows of energy occur. While the flow of energy from land to water has been quite extensively studied, comparatively few studies have investigated the importance of energy flows in the other direction. Nevertheless, recent studies show that aquatic-derived energy (i.e. ‘aquatic subsidies’, most often in the form of emerged aquatic insects) is very important for terrestrial consumer community structure and dynamics, and that human impacts on aquatic systems may have negative consequences also for terrestrial organisms via modifications of such energy flows. In this project, we therefore investigate which factors drive aquatic subsidies, how terrestrial communities depend on aquatic subsidies, and what consequences quantitative and temporal changes in aquatic subsidies have for terrestrial consumers. The studies are conducted along both pristine and anthropogenically disturbed streams in northern Sweden, and we quantify effects both through numerical responses and isotope analyses. Our aim is to better understand the importance of aquatic subsidies for the structure, dynamic and function of terrestrial systems, and thereby to aid in the development of successful conservation and restoration strategies of natural and impacted ecosystems.
